Today, calling party identification (Caller ID) service is widely available in most industrialized countries. A fundamental method and apparatus for providing Caller ID service in a telephone communication system are disclosed in U.S. Pat. No. 4,551,581 granted Nov. 5, 1985 to C. A. Doughty, and a fundamental method and apparatus for receiving Caller ID information at a telephone receiver are disclosed in U.S. Pat. No. 4,582,956 granted to C. A. Doughty on Apr. 15, 1986. The disclosures of these patents are incorporated herein by reference.
Conventional Caller ID equipment provides an identification of the calling party to the called party's telephone customer premises equipment before a telephone connection is established. That is, the Caller ID information is provided to the called party while his telephone equipment remains in an “on-hook” state. Specifically, the central office alerts a called party to an incoming message by ringing his telephone equipment. A ringing signal is applied to the telephone equipment intermittently, with a silent interval being provided between consecutive rings of telephone equipment. When the called party lifts the telephone receiver, the telephone equipment assumes an “off-hook” state, but prior to that time, it remains in an “on-hook” state. Generally, caller ID information is transmitted to the called party's telephone equipment during the “on-hook” state in the silent interval between the first and second rings, but it may come prior to the first ring, after which the Caller ID information is displayed to the called party.
A shortcoming of conventional Caller ID service is that it does not identify the actual calling party, but only the telephone equipment from which the call is being made. When a party is identified, it is registered owner of the telephone equipment from which the call is being made. Thus, when the calling party calls from telephone equipment which is shared among many individuals, from a telephone at a site he is only visiting, from a pay telephone, or through a PBX, the called party cannot identify the actual calling party without going “off-hook” on this telephone equipment and speaking to the calling party. This, however, defeats the intended purpose of Caller ID service.
In accordance with the present invention, a Caller ID service is provided which permits the calling party to speak a real time audio message that can be received and played by the called party's Caller ID equipment while his telephone equipment remains in the “on-hook” state. A calling party which has Audio Caller ID (ACID) service would speaker a short audio message before dialing the called party. That message is converted to digital form, optionally compressed, and transferred to the called party in a manner similar to conventional Caller ID information. The called party's Caller ID equipment operates in the conventional manner, except that the received Audio Caller ID signal is recognized as an audio signal. At the site of the called party, a decoder is provided to convert the digital signal to an analog audio signal, and this analog signal is provided to a speaker, which plays back the calling party's audio message.
Preferably, conventional Caller ID operation is preserved when Audio Caller ID service is provided. This is achieved by sending the Audio Caller ID data in the silent interval following the second ring. The audio Caller ID equipment treats any signal received after the first ring as a conventional caller ID signal and any signal received after the second ring as an Audio Caller ID signal. An Audio Caller ID receiver could then store conventional Caller ID information in the conventional manner (i.e. allowing the called party to view information about a predetermined number of received calls), while also permitting an audio message or clip to be stored in association with each call. The Audio caller ID may also be sent during rings or regardless of rings.